Power transmission and electric braking



A; F. BATCHELDER.

POWER TRANSMISSION AND ELECTRIC BRAKING. 7

APPLICATION FILED SEPT- I I, 1920- 1,421,894 Patented July 4,1921,

Inx/enbdr. Asa F'. Batahelder,

.His Aeb orne y.

UNITED -QSTZAIIBS Q JA TENT Lorr ASA r. BAToHEL-DER, QRscI-IENEGTADY, EW YORK, AssronoRx-ro GENERAL] time.

:TRIQCQMPANY, A. CORPORATION OFgNEW .gYOBK.

it '1 .Specificatin ofLetters Patent.

Patented July 4, 1922.

- Applicationfiled September 11, 1 92Q.- Serial No." 409,647.

r T 0 all whom it may concern a citizen of the United States, residing at schenectady, in the county of Schenectady,

State of New York; have invented certain new anduseful Improvements 1n Power- Transmission and Electric" Braking, of

' which the following is a specification.

' My invention relates to systems of power transmission and electric braking,rand in particular to systems wherein a plurality of" dynamo electric'machines are caused toopcrate as motors to drive a load, or asgener atorsdriven by-the load to retard the load.

Although not limited to such use, my in vention has a particular usefulness in the control of theelectric driving motors ofan ation if'that is desired; Other objects of-my Be it known that I, AsA F=. BATGHELDER,

invention will be fully-pointed out -.in the followlng description" ofthe invention Reference is had to the accompanying-drawing in which I have shown 1n--very simplified diagram an embodiment of my invention for purposes of illustration and in which a plu- .ra'lity" of dynamo electric -machines-:;havins;

a-rmatures A, B, C, D, E and F and fields d, b, 0, d, cand f respectively-are operatively connected to a supply circuit indicated as a trolley wire 1O,=the other side of-the supply electric vehicle, such for instance as an elec-ji' tric locomotive or thelike.

ll'ly invention provides improved means" wvhereh the braking effect is very nicely controlled in a simple and eflective manner,

and the arrangement is. such that when the" systcmis used to brake a'load electrically"- by delivering energr 1 to a source oi. supply,

' fluctuations in the voltage of the source of supply and in the braking .current'are. auto-- matirtally compensated for. A simple-and effective arrangement provided which hasan inherently compensating effect to take.

care of these fluctuations.

My system 1s of the type in wh1ch,.dur-

' ingbraking, a portion of the machines oper-- ates as an exciter for the remainder ofthe machines. In particular, my invention relates to a system of this character in which the dynamo electric machines are series wound and the exciter portion of the'ma chines is self-excited. One of the obpectsiof my invention is to provide an improved ar rangcment for electr c braking which 1nhercntly compensates for changes of brak which the braking effect can'be very accu-m rately controlled at the will of the operator; in a simple and effective manner. A still further object is to provide a braking ar rangement in which a portion of the ma chlnes operates as a self-excited exciter for the remainder of the mach1nes,'wh1ch will operate satisfactorily for motoring opera vcircuit being the ground --connection as shown. Thesedynamo electr c machines are adapted to-operate as series-motors to drive :the load, and they -may be-conn'ectedin" variousrelations-such as series; seriesparallel, or parallel. I have not illustrated a particular form "of controller for connecting the motors in various relations for; motoring or -forestablishing the braking connections, since those skilled; inythe art will readily supply a controller and connections whereby the motors may be connected in anyjrelation desired. In thegdrawingl have merely indicated a very 'simplifieddiagram ofithe connections established during electric braking, since this is of the essence of my invention. It will be observed that the-series fields of the machines-are connected in a V local circuit with the armatures E and F of the cxciter portion of the machines; a It will also beobserved that the exciter armatures l) and F areconnected in multiple with each other in series-relation with the-armatures of the remainderof-theymachines across the supply circuit, and that the armature E has a resistor 11 in series therewith and the armatureF has a resistor 12 in series there with. These resistors 11 and 12 I have termed balai'icing resistors, since. a part of their functions is to. balance the loads of the ex citers; Theseries fields c and f of the exciter portion of the machines.areshuntedi'by meansof a variable resistor 13 whichprovides a means for varying the excitationiof the exciters and thereby varying the braking :eflect by shunting a. portion of the current in the local circuitaround the exciterfield windings. It'will: be observed that during braking the braking; current has a path throughthe resistors 11 and 12, the exciter armatures E and F, and through the'armatures D, G, B" and Act the remainder'of the dynamo electric machines, and that only the current in the local circuit flows through the field windings of the machines. The lirection of current in the braking circuit and in the local circuit is as shown by the arrows. The respective loads of the exciters may be varied by varying the resistors 11 and 12, and the multiple circuit, including the exciter armatures, is the only circuit which carries the combined braking and excitation current. That means that the armatures l1) and F and their respective field windings c and may be exactly the same as the armatures and field windings of the remainder of the machines. Those skilled in the art will readily perceive the advantages of an arrangement in which all of the machines of the system are similar to each other.

The resistors 11 and 12 have important functions in my system. In the first place, these resistor-s provide means whereby the exciters may carry their full portion of the load, and the distribution of load between the exciters may be apportioned. Because of the fact that the field windings of the machines are relatively highly inductive as compared to the armatures of the exciters, the resistors provide a resistance in the armature circuit of the machines which permits the field windings to be sulficiently energized at .the start of both the motorin and the brale ing operations. Furthermore, if the machines were connected as shown and the scheme used for motoring while the connections are as shown for regenerating, the resistors make it possible for the machines to operate as motors, since without these resistors the field windings of the machines may not receive a su'ilicient amount of current. In case a plurality of sets of the same number of machines are used, the sets being connected in multiple, each set connected in accordance with my invention, the resistors provide a means whereby the respective loads of the sets of machines may be balanced so that one set of the machines may deliver substantially the same braking effort as the other set or sets of machines. Incase a plurality of sets of machines are connected in series relation, the resistance value of the resistors in each set will preferably be less than when a single set is used or a plurality of sets in multiple, for the reason that the compensating effect of each set of resistors will be supplemented by the compensating effect of the other set of resistors. It the voltage of the supply circuit should suddenly drop while the machines are regenerating, the current delivered to the supply circuit will also suddenly increase, but this will cause a greater voltage drop across the resistors 11 and 12, and that will decrease the effective voltage applied to the field windings and also decrease the effective voltage of the excitors so that the excitation of all of the machines is decreased. A balance is very quickly reached and a stable condition etfected. In case there should. be an increase of line potential, the voltage oi the machines would be correspondingly increased, by reason of the inherent characteristics of the arrangement. The arrangement is therefore one in which the compensating effect for changes in line potential and in braking current is inherent in the arrangement, and no extra automatic apparatus is necessary. In order to vary the braking effect, the resistor 13 which shunts the excite]: fields will be varied.

It will also be observed that in case the generated potential is less than the potential of the supply circuit, the direction of" current in the armature circuit of tl e machines will be reversed, but the direction of current through the fields will remain the same as during braking. This will cause the machines to operate as motors. The arrangement has thus the advantage that either braking or motoring operation may be had as desired without changing the circuit connections. The motors E, e, and F, f, will have a characteristic which is in the nature of a shunt characteristic, and the remainder of the machines will have a characteristic which is in the nature of a series characteristic.

It will be understood that the machines are connected to either drive the load, such as a vehicle, or to be driven thereby so as to operate as braking generators, although it will be obvious in so far as certain aspects of my invention are concerned that the machines need not all be similar, nor need they all be used. during motoring in case they are not all similar. Thus the exciter portion of the machines may he designed solely for this purpose and be driven by the load, but not necessarily used to drive the load.

In accordance with the provisions oi. the patent statutes, l have described the principle of operation of my invention, together with the apparatus which I now consider to represent the best embodiment thereot, but I desire to have it understood. that the apparatus shown only illustrative and that the invention can be carried out by other means.

What- I claim as new and desire to secure by Letters Patent If the United States, is z-- 1. In a system oi electric braking; a plurality of operatively connected dynamo electric machines having severally a riuature and field windings, a portion oil said machines operating as a self-excited cxcitcr connected in a local circuit with the fields of all. of said machines, a resistance in the said local circuit, and connections whereby the braking current has a path thro 'h the .cid resistance and the armatures 0t it; machines. the excitation oi all oi? said machines is varied responsively to the variations of the lll 'l llO llS

hrakingwcurrent, and only the current in'the local circuit passes through thefieldwindings of said machines.

2. In a system of electric braking, a -plu-- rality of operatively connected dynamo e1ectric machines, having severally armature and field windings, a portion of. said machines cuit, means for varyingthe current in .the-

operating as a self-excited exciter connected in local circuit witht-he fields of all of said machines, a resistance in the said local cireXciter field windings, and connections whereby the braking curren't has a: path through the said resistance and thearma tures of said machines, and onlynthe'current in the local clrcuit passes throughthe field windings of said machines.

3. In a system of electric braking, a plu-- rahty ofoperatively connected dynamo elec-" tric machines, a portion of said machines opcrating as a self-excitedexciter connected in a local circuit with the fields of all of SELlCl'IIliL-L.

chines, a resistance in the said local circuit;

7 means for shunting a portion of the cur-f rent in said local circuit around the exciter field wnidings, and connect onswhereby the braking current has a path througlrthesaid resistance and thearmatures of said machines,the excitation of all of said machines is varied responsively to the variations ofthe braking current, and onlythe current in the local circuit passes'through the field windings of said machines.

lam [1'1 a system of electric braking, a pluralityo'f operativelyconnected dynamo elec-' the braking current, and only the current in the local circuit passes through. the field windings of saidmaclnnes.

5..I'n a'system of electric braking, a plurality of similar dynamo electric machines having severally armature and field wind-- ings, a plurality of Which operate assel'lfexcited exciters connect-ed in-multiple witheach other and in series with the remainder oi the armatures, the series fields of all the machines being connectedin a local circuit with the exciter armatures so that only the local excitation current passes through the field windings of the machines and the excitation of all of the machines is varied responsively to variations of the braking cur-1* rent. a

6. In a system of electric braking, a plu- -rality of "similar dynamo electric machines having severally armature 'and field wind ,ings, a plurality of said machines operatazing as self-excited exciters with their arma- ;:tures connected in multiple with each other in'series with the remainder of the armatures, the field windings: of all themachines being connectedin a localcircuit with the exciter armatures, so that only the local excitation'current :passes through the field windings of the machines and the excitation of all of the machines isvaried responsively to variations ofi-the braking current and means for varying "the-current in the exciter fieldwindings so as to vary the braking ef- :fect.

' 7.In a system of electric braking, a plu .rality' ofv similar dynamo electric machines having: severally-armature and field windings, aplurality' of :said /machines operating asself-eXci-ted exciters' with their arma- .tures" connected in multiple with each other in series'withcthe remainder of the armatures'the field windings of'all the machines :being connected in a local circuit with the exciter .armatures,' so that only the local ex- Jcit-ation currents passes through the field windings of the machines and the excitation of all o'fthe machines isvaried responsively to variations of: the braking current and meansfor shuntinga portion'of the current field: windings.

8..In asystemiof electric braking, aplurality of similar dynamo electric machines having severally armature and field windings, two of thearmatures of which operate as self exoited exciters connected in mul tiple' with each other in series with the re-' mainder of *the armaturesythe fields of all the machines being connected in a local circuit with the exciterarmatures, so that only the local excitation current passes through the field windings ofithc machines.

9; In asystem'of electric braking, a plurality ofdynamo'electric machines having of the armatures"ot -which operate as-selfexcited exciters connected in multiple with each other in series with the remainder of the armatures, the fields of all the machines being connected in a localcircuit with the exciter armatures, so that only-the local excitation current passes throughthe field windings of the machines and the excitation of all of the machines is varied responsively to variations of the braking current and means for varyingv the current in the exclter field w1nd1ngs so as to vary the braking elfect.

10. Ina system'of electric braking, a pluhaving '-severally-'armature and field windings, a plurality' or said machines operating as-exciters withltheir armatures connected in multiple-with each other in series with the remaiinder of the armatu'res, the

in the said localcircuit around the exciterseverally armature and field windings, two

rality 'of-similar dynamo electric-machines fields of all the machines being connected in a local circuit with the exciter armatures, so that only the local excitation current passes through the field windings of the machines and the excitation of all of the machines is varied responsively to variations of the braking current and a shunt path of variable resistance around the exciter field windings.

1.1.. In a system of electric braking, a plurality of operatively connected dynamo electric machines, having severally armature and field windings, a portion of which operate as self-excited exciters for the said machines, a balancing resistance in circuit with the armature windings of said portion, and connections whereby the field windings of said machines are connected in series rela-' tion in a local circuit to the exciter portion of the armatures and the balancing resistance, the connections being such that the braking current has a path through the balancing resistance and the armatures of said machines, and only the current in the local circuit passes through the field windings of the machines.

12. In a system of electric braking, a plurality of dynamo electric machines having severally armature and field windings, a plurality of which operate as exciters with their armatures connected in multiple with each other in series with the remainder of the armatures, the fields of all of the machines being connected in a local circuit with the eXciter armatures, so that only the local excitation current passes through the field windings of the machines and the excitation of all of the machines is varied responsively to variations of the braking current and a resistor connected. in series with each exciter armature.

13. In a system of electric braking, a plurality of dynamo electric machines having severally armature and field windings, a portion of said machines operating selfeXcited furnishing excitation for said machines, a balancing resistance in the armature circuit of said eXciter portion of the machines, a resistor shunting the field windings of the exciter portion of the machines, and connections whereby the braking current has a path through the said balancing resistance and only the excitation current passes through the field windings of said machines.

14;. In a system of electric braking a plurality of dynamo electric machines having severally armature and field windings, a plurality of which operate as self-excited exciters with their armatures connected in multiple with each other in series with the remainder of the armatures, a resistor in the armature circuit of each exciter, the fields of all of the machines being connected in a local circuit with the said multiple circuit having the exciter armatures therein, so that only the local excitation current passes through the field windings of said machines and the excitation of all of the machines is varied responsively to variations of the braking current, and a shunt path of variable resistance around the exciter field windings.

15. In a system of regenerative braking, a supply circuit, a plurality of similar (lynamo electric machines operatively connect ed to the supply circuit, a portion of the said machines operating as exciters with their armatures connected in multiple relation in series with the armatures of the remainder of the machines, a resistor in the circuit of each eXciter armature, the field windings of all of said machines being connected in series relation in a local cir cuit to the said multiple circuit including the exciter armatures, so that only the local excitation current passes through the field windings of said machines and the excitation of all of the machines is varied responsively to variations of the braking current and a variable resistor shunting the field windings of the exciters.

16. In a system of power transmission and regenerative braking, a source of supply, a plurality of dynamo electric machines connected to the source, a portion of said machines operating as a self-excited exciter connected in a local circuit with the field windings of said machines, and connections whereby all of the machines operate either as braking generators or as motors, depending on the generated potential of the machines.

17. In a system of power transmission and regenerative braking, a source of supply, a plurality of dynamo electric machines connected to the source, a portion of the arma-tures of said machines connected in a local circuit with the field windings of said machines, the armatures of said machines operatively connected to each other across the source of supply, the said portion oper' ating as a self-excited exciter for the remainder ot the machines for braking, a re sistor in the said local circuit, and conncctions whereby during braking the braking current passes through the armatures of said machines and only the current in the local circuit passes through the field windings of the machines, and during motoring the direction of current is reversed in the armature circuit of said machines and remains the same in the field circuit.

18. In a system of power transmission and regenerative braking, a source of supply, a plurality of similar dynamo electric machines connected to the source, a portion of said machines operating as a self-excited eXciter connected in a local circuit with the field windings of all of said machines, a

resistor in the armature circuit of the eX- citer portion of the machines, and connections whereby all of the machines operate either as braking generators or as motors, depending upon the generated potential of the machines. r

19. In a system of power transmission and regenerative braking, a source of supply, a plurality ofsimilar dynamo electric machines connected to the source, two of said machines having their armatures connected in multiple operating as self-excited exciters connected in a local circuit with the field windings of said machines and in series with the remainder of the armatures across the source of supply, a resistor in series with each exciter armature, and connections whereby all of the machines operate either as braking generators or as motors, depending upon the generated potential of the machines.

In witness whereof, Ihave hereunto set my hand this 10th day of September, 1920 ASA F. BATCHELDER. 

